Hydroxychloroquine Sulfate is a synthetic quinine derivative commonly used as an antimalarial drug [1]. It is also useful in managing systemic lupus erythematosus, rheumatoid arthritis, and other diseases. Also acts as an inhibitor of autophagy and toll-like receptor 7/9(TLR7/9) [1-3].
Five micromolar Hydroxychloroquine sulfate or chloroquine also has no measurable effect on intracellular pH, although these concentrations can inhibit TLR9 or 7 signaling induced by DNA or RNA ligands [4].
Hydroxychloroquine sulfate is prescribed for the treatment of lupus, and both Hydroxychloroquine sulfate and its analog chloroquine inhibit TLR7 and 9 signaling [4].
References:
[1] Ben-Zvi I, Kivity S, Langevitz P, et al. Hydroxychloroquine: From Malaria to Autoimmunity. Clin. Rev. Allergy Immunol, 2012, 42 (2): 145-153.
[2] Yildirim-Toruner C, Diamond B. Current and novel therapeutics in the treatment of systemic lupus erythematosus. Journal of Allergy and Clinical Immunology, 2011, 127 (2): 303-312.
[3] Swierkot J, and Szechinski J. Methotrexate in rheumatoid arthritis. Pharmacol. Rep, 2006, 58 (4): 473-492.
[4] Lamphier M, et al. Novel small molecule inhibitors of TLR7 and TLR9: mechanism of action and efficacy in vivo. Mol Pharmacol, 2014, 85 (3): 429-40.